Alpha-isatin anilid.



UNITED STATES PATENT OFFICE.

TRAUGOTT SANDMEYER, OF BASLE, SWITZERLAND, ASSIGNOR TO JOHN B. GEIGY &CO., OF SAME PLACE.

ALPHA-ISATIN ANlLlD.

SPECIFICATION forming part of Letters Patent N6. 647,281, dated April10, 1906.

Application filed December 7, 1899.

T0 at whom it may concern? Beit known that I, TRAUGOTT SANDMEYER, acitizen of the Swiss Confederation, residing at Basle, Switzerland, haveinvented certain new and useful Improvements in Alpha-Isatin Anilid, ofwhich the following is a specification.

To the present invention (for which patents have been applied for inGermany, G 13,633, dated July 17, 1899; in France, No. 279,418, datedAugust 2, 1899; in England, No. 15,497/99, dated July 27, 1899; inBelgium, dated August 1, 1899; in Russia, dated August 1,1899; in Italy,dated August 1, 1899; in Spain, No. 2 1,756, dated August 1, 1899; inAustria, dated August 1, 1899, and in Hungary, dated August 1,1899, No.13,536)

I was directed by the observation that isonitrosoethenyldiphenylamidinis easily transformed into a derivative of isatin, (see application,Serial No. 739,506, filed December 7, 1899,) which observation led me tosuppose that also other bodies relating to the former compound might becapable by forming a cycle of conversion into alpha-isatinanilid whentreated with concentrated sulfuric acid. It was necessary to especiallyconsider those two compounds which by conversion of the isonitrosogroup, either in the cyan or in the carboxyamido group, could be treatedas intermediary bodies, according as the action of the sulfuric acid wassupposed to be a dea which color gradually fades.

priving of water or only a transforming action.

With regard to the cyanid it is identical with thehydrocyancarbodiphenylimid pre pared by Laubenheimer (Bert. B622, XIII,2155) in combining hydrocyanic acid with carbodiphenylimid.Laubenheimermentions as a characteristic reaction of this body that inheating with concentrated sulfuric acid it gives a red-colored solutionwhich by dilution with water becomes clear. When a few drops of thissolution are poured into water and some caustic-soda lye added, anintensely-blue-colored solution is obtained,

The surprising conformity in the appearance of the colors in thisreaction with those which appear by heatingisonitrosoethenyldiphenylamidin with concentrated sulfuric acid,diluting with water, and neutralizing with caustic-soda lye $erial No.7395508. (Specimens) By dissolving this compound in Warm sulfuric acidthe interior condensation takes place, forming alpha-isatinanilid andseparating out ammonia and sulfureted hydrogen, which latter immediatelyacts upon the sulfuric acid, forming sulfurous acid and separatingsulfur:

CIS

or in the tautomeric pseudoform IIydrocyancarbodiphenylimid has beenprepared by Laubenheimer in two different 10o ways-first, by boilingthiocarbanilid in alcoholic solution with mercuric cynanid for a longtime, and, second, introducing hydrocyanic acid in excess into afreshly-prepared solution (according to VVeith, Ber-Z. Ber., VII, 1306)of unpolymerized carbodiphenylimid in benzene. Both methods are unsuitedfor practical use.

The process described can be easily carried out with any quantities andwithoutmuch danger if the removal of the sulfur is brought about bybasic carbonate of lead in the presence of a soluble cyanid-as, forinstance, potassium-cyanid. The carbonate of lead deprives thethiocarbanilid of sulfureted hydrogen in forming sulfid of lead, thenascent carbonic acid decomposes the potassiumcyanid and the nascenthydrocyanic acid combines instantaneously with the liberatedcarbodiphenylimid,for1nin g hydrocyan carbodiphenylimid.

The following examples illustrate the manner in which my invention canbest be carried into practical effect. The parts are by weight:

First phase of the process-Pr0ducfion of hydrocyancarbodc'phenylimid.Theprocess for the production of this substance mentioned by Laubenheimer(Berichte der Deutsche-n Ohemt'schen Gesellschaft, Vol. XIII, p. 2155)is unsuited for practice on ac count of the use of free hydrocyan-icacid or of mercuric cyanid. Without the slightest dangerhydrocyancarbodiphenylimid can be prepared in the following Way: In avessel fitted with a stirrer are dissolved seven parts ofpotassium-cyanid of ninety-eight per cent. (or the equivalent quantityof ordinary potassium-cyanid of less percentage or of sodium cyanid) intwenty parts of water. To this solution are added thirty parts of basiccarbonate of lead, (white lead,) twenty-one parts of thiocarbanilid, andfifty partsof alcohol. Then, while stirring, the solution is slowlyheated up to 50 to centigrade. After a short time the reaction isfinished, which is indicatedwhen a test filtered off from the sulfid oflead and boiled with carbonate of lead does not blacken it. When cold,the contents of the vessel are diluted with water and the insolublemixture of sulfid of lead and liydrocyanid is filtered off. Afterpressing and drying,the hydrocyancarbodiphenylimid is separated from thesulfid of lead by extraction with alcohol or ether. The sulfid of leadis transformed by hydrochloric acid into chlorid of lead, and this againinto white lead.

The preceding method may be varied in different Ways withoutmodification of the final result. For instance, the alcohol may be leftout; but in this case the finely-pulverized thiocarbanilid must be mixedvery carefully with the white lead and the aqueous solution ofpotassium-cyanid of about ten per .cent. The transformation takes placeat 30 to 40 centigrade,though somewhat slower. Further, the White leadcan be substituted by other basic lead salts, such as oxychlorid oflead.

Second phase of the 1]7'OC6SS PTOdUCi iO7t of a thioanrid. from7tydrocycmcm'bodzpheng Z- imicL-Jn a closed vessel fitted with a stirrertwenty parts of finely-pulverized hydrocyan carbodiphenylimid are mixedwith fifty parts ofa solution ofyellow ammonium sulfid which has beenprepared by introducing three parts of sulfureted hydrogen intoforty-five parts of aqua-ammonia of twenty-one to twentytwo per cent.,and by further dissolving in the colorless solution of ammonium sulfidthereby formed 2.5 parts of pulverized sulfur,

.or by introducing five parts of sulfureted hydrogen into the abovesaidforty-five parts of aqua-ammonia and allowing the solution to stand forseveral days till it assumes a deep-yellow color. The formation of thethioamid is accelerated by stirring at a temperature of 25 to 30centigrade, and completion of the reaction is indicated when a filteredand washed test dissolves completely in diluted hydrochloric acid. Oneor two days are required for the reaction. The thus-formed thioamid ofthe formula which is a lemon-colored crystalline powder, is thenfiltered 01f, washed, and dried. Recrystallized from alcohol it formsbrilliant thin golden-yellow prisms, melting at 161 to 162 centigradeand dissolving in diluted mineral acids and, if warmed, also in dilutedcaustic-soda lye.

Third phase of the processP-roducti0n of aZphct-isatimmilid.-Eightyparts of concentrated sulfuric acid are heated up to centigrade. Thenthere are added gradually, with stirring, twenty parts of theabove-mentioned well-dried thioamid. Care must be taken that the rise oftemperature, which occurs after every addition, does not exceedcentigrade. Under vigorous development of sulfurous acid the thioamiddissolves, and the sulfuric acid assumes first a deepbrownish-violetcolor and finally turns to an intensely-yellowish red. When all ismixed, the temperature is raised to to centigrade till the developmentof the sulfurous acid ceases. After completely cooling the concentratedsulfuric solution is poured, under constant stirring, into a solution ofan excess of carbonate of soda with a sufficient quantity of ice. Thealpha-isatinanilid is precipitated in brown crystalline flocks and isfiltered, pressed, and dried at low temperature. By recrystallizationfrom benzene or carbon disulfid it can be separated from the sulfur setat liberty by the reaction and mixed with the alpha-isatinanilid. Alphaisatinanilid crystallizes in brilliant dark-brownish violet almost-blackneedles, melting at 126 centigrade and easily soluble in warm alcoholwith a yellowishbrown shade; in ether, in benzene, and carbon disulfidwith a raspberry-red shade. It is easily soluble, likewise, in organicas well as in mineral acids with a yellowish-red shade.

When the yellowish-brown alcoholic solution is mixed with somecaustic-soda lye, the color turns to an intense blue, growing pale aftera a short time.

What I claim as new, and desire to secure by Letters Patent, is-

As a new product, the herein-described alpha-anilid of isatin, havingthe formula and obtained by producinga reaction of basic carbonate oflead (white lead) upon thiocarbanilid in the presence of analkalicyanid,

treating the thus-obtained hydrocyancarbodiphenylimid with a solution ofyellow ammonium sulfid, and transforming the thus prepared thioamid byhot sulfuric acid, said alpha-anilid of isatin forming brilliantdarkbrownish violet nearly-black needles melting at 126 centigrade,easily soluble in warm alcohol with a yellowish-brown shade, in ether,in benzene and carbon disulfid with a raspberry-red shade, easilysoluble in organic as well as in mineral acids with a yellowish-redshade, and the yellowish-brown color of its alcoholic solution turningto an intense blue by addition of caustic-soda lye and growing paleafter a short time, substantially as set forth.

In testimony that I claim the foregoing as my invention I have signed myname in presence of two subscribing witnesses.

TRAUGOTT SANDMEYER.

Witnesses:

GEORGE GIFFORD, ALBERT GRAETER.

